#define _CRT_SECURE_NO_WARNINGS
#pragma warning(disable:6031)
#include<string>
#include<iostream>
using namespace std;
int main()
{
	string s1;
	string s2("hello world");
	string s3(10, 'm');
	string s4(s2);
	string s5(s2, 4, 5);
	cout << s1 << endl;
	cout << s2 << endl;
	cout << s3<< endl;
	cout << s4 << endl;
	cout << s5 << endl;
	return 0;
}
